linux-kernel - Re: [PATCH v3 2/5] clk: imx: fracn-gppll: correct PLL initialization flow

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Message-ID: <ZynsdXx3McoW9SK5@linaro.org>
Date: Tue, 5 Nov 2024 11:59:17 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc: Abel Vesa <abelvesa@...nel.org>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Aisheng Dong <aisheng.dong@....com>, linux-clk@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>,
	Jacky Bai <ping.bai@....com>
Subject: Re: [PATCH v3 2/5] clk: imx: fracn-gppll: correct PLL initialization
 flow

On 24-10-27 20:00:08, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 
> Per i.MX93 Reference Mannual 22.4 Initialization information
> 1. Program appropriate value of DIV[ODIV], DIV[RDIV] and DIV[MFI]
>    as per Integer mode.
> 2. Wait for 5 μs.
> 3. Program the following field in CTRL register.
>    Set CTRL[POWERUP] to 1'b1 to enable PLL block.
> 4. Poll PLL_STATUS[PLL_LOCK] register, and wait till PLL_STATUS[PLL_LOCK]
>    is 1'b1 and pll_lock output signal is 1'b1.
> 5. Set CTRL[CLKMUX_EN] to 1'b1 to enable PLL output clock.
> 
> So move the CLKMUX_EN operation after PLL locked.
> 
> Fixes: 1b26cb8a77a4 ("clk: imx: support fracn gppll")
> Co-developed-by: Jacky Bai <ping.bai@....com>
> Signed-off-by: Jacky Bai <ping.bai@....com>
> Signed-off-by: Peng Fan <peng.fan@....com>

Reviewed-by: Abel Vesa <abel.vesa@...aro.org>

> ---
>  drivers/clk/imx/clk-fracn-gppll.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-fracn-gppll.c b/drivers/clk/imx/clk-fracn-gppll.c
> index 591e0364ee5c113859a7b6271c8c11e98a0e0ffc..4749c3e0b7051cf53876664808aa28742f6861f7 100644
> --- a/drivers/clk/imx/clk-fracn-gppll.c
> +++ b/drivers/clk/imx/clk-fracn-gppll.c
> @@ -303,13 +303,13 @@ static int clk_fracn_gppll_prepare(struct clk_hw *hw)
>  	val |= POWERUP_MASK;
>  	writel_relaxed(val, pll->base + PLL_CTRL);
>  
> -	val |= CLKMUX_EN;
> -	writel_relaxed(val, pll->base + PLL_CTRL);
> -
>  	ret = clk_fracn_gppll_wait_lock(pll);
>  	if (ret)
>  		return ret;
>  
> +	val |= CLKMUX_EN;
> +	writel_relaxed(val, pll->base + PLL_CTRL);
> +
>  	val &= ~CLKMUX_BYPASS;
>  	writel_relaxed(val, pll->base + PLL_CTRL);
>  
> 
> -- 
> 2.37.1
>